Hey Rich,
Problems like these can be very frustrating. Not lecturing to you, but take a
deep breath. You will get it going. I know the tendency is to throw the baby
out with the dirty diaper (or however that saying goes) but from my experience
and what I am reading we have a very good amp in the KXPA100. I started my
career in electronics 42 years ago and 9 times out of 10 the reason for a
problem is really quite obvious - once it is fixed that is. :)
I don't see where the schematic and firmware is available for the KXPA100. It
may be, I just don't see it. But lets do some logical troubleshooting. First,
the front plate and the nut have nothing to do with the operational problem.
Granted, it shouldn't have happened but it did. Elecraft made good on it so
that one is no reason to be talking about returning the amp. The two are
simply not connected. I will say that I had parts problems with mine also -
not Elecraft's but my bone-headed failure to read the Eratta. I twisted off a
standoff lug. Elecraft sent me a new one. And guess what, I wasn't really
short lock washers either, I just didn't read the part that said I didn't need
them under the standoffs. Duh! So it sounds like your parts situation is OK
now.
So, the KX3 seems to work fine going around the amp. That tells me your
problem is definitely in the amp. OK you knew that. But there is no need to
be changing out the tuner and what not. The problem is in the KXPA100. I buy
that. It appears the KX3 is talking to the KXPA100 just fine. It recognized
it and adjusted itself for proper power etc. That is an RS232 serial interface
so there isn't much that can go wrong with it. All of the data goes down 1
wire. Unless it intermittently and randomly just starts switching or tuning or
changing something, I wouldn't suspect the RS232 link. It should either work
(as it appears to be doing) or it doesn't. So there is no need to mess with
that interface.
The SWR of 99.9 is probably not so puzzling when you think about it. What
would happen if you didn't have any antenna connected? Or if the antenna
connector or cabling were shorted? In theory, the SWR would be infinite. But
I suspect the firmware in the amp can't handle infinite SWR too well. So I am
guessing that when SWR goes over a particular limit it just says, "The SWR is
too freekin high. I am just going to display 99.9 to tell the user it is way
out of wack." I suspect that what is happening is that your antenna is not
really connected to the radio when you think it should be. If your amp is
seeing an open antenna line when it tries to transmit, you should see what you
are getting. Now stick with me. The fact that you are seeing some weird
switching indications between ANT1, ANT2, and Bypass, tells me that you may
have your coax connectors inside the amp connected to the wrong receptacles on
the board. I don't know how that would effect the LED lights and su
ch, but it could sure mess up operations. Ask me how I know? When I first
powered mine up, I noticed the KX3 was very very quiet. More so than it should
be. So I started playing around and discovered that when I connected my
antenna to the ANT2 connector I got an increase in noise. HMMM! Switch to
Antenna 2 on the KX3 and the noise drops to nothing. Move the antenna cable
over to the ANT1 connector and it comes back. I had crossed the ANT1 and ANT2
connectors when I plugged them into the board.
Now in your situation, you may have something similar. I don't know what the
switching circuits and relays all look like in there, but it appears that your
problem could be similar. There is one symptom you mentioned that I can't
answer. You said you were getting 30 or 40 watts out of the big amp instead of
300-400. I don't understand that. If the RF drive is not going into the amp,
I would say you should get zero output. Maybe there is something going on
there with keying the amp with no drive that would cause some strange meter
readings. Or maybe the coax cable in your KXPA100 is partially open or shorted.
Anyway, I would open up the KXPA100 and double check those connectors to be
sure they are plugged into the appropriate sockets. You could also get an
infinite SWR if a cable were almost fully shorted. Check for that also. Also
check to make sure you didn't flex the cables so much that one broke off the
back of the SO239 connector. Finally, double check to make sure that when you
plugged in the tuner board you didn't bend or miss a pin in one of the
connectors. Just triple check, I know you have double checked. Then hook up
your antenna again to the KXPA100 (the big amp isn't needed for this
troubleshooting) and use the listen test I mentioned earlier. You should be
able to tell pretty quickly if you have a good path between the antenna and the
radio through the KXPA100. You should then be able to switch antennas and tell
th
